Pardon the upcoming rant. There is nothing personal about what I am about to say. I just feel that it needs to be said, I will say it repeatedly, and I am sure I will upset a couple people by saying it, but as long as discussion is reasonable and rational, I will hear out other people. I know there are good arguments against my position of "amount of caffeine in milligrams doesn't matter".

I am mildly irritated by this question of "what's the amount of caffeine in tea". It comes up often, but I don't understand why so many people need exact amounts. There are two reasons why levels of caffeine in teas aren't helpful metrics for measuring things such as stimulating effects on the body. First, it's extremely difficult to measure caffeine levels, because, given a type of tea, there are so many variables that affect the amount of caffeine actually consumed. Second, even in two different situations when the amount of caffeine consumed are supposedly the same, the actual effects on the body can be wildly different. Here is why exact amounts of caffeine are so difficult to measure: The amount of caffeine in a cup of tea depends on:

The type of tea

The varietal of tea bush

The age of the tea bush

The time of year the tea bush was harvested

Weather and climate conditions

How the tea was processed

Parts of the tea bush included in the tea (stems, young leaves, old leaves, buds, etc.)

How the tea was brewed - including state of the leaves during consumption (broken-down leaves will release more caffeine than whole leaves) - type of water, temperature, time, ratio, etc.

Whether any tea leaves were consumed in addition to the liquor (e.g., matcha)

In other words, if somebody claims "there is x milligrams of caffeine in y tea", consider that all of the preceding variables will affect the final amount ingested, so the error bars or variance on x will be quite large. More importantly, here is why the amount of measured caffeine in any food or drink item is not a good metric for measuring effects such as stimulation:

The amount measured by researchers or scientists is only meaningful if you consume the beverage when it is in exactly the same state as it was during the laboratory measurements.

Your body easily builds tolerances to caffeine and other stimulants after repeated exposure, and then loses tolerance with lack of exposure

The effect of stimulants such as caffeine on the body depends highly on time of day, amount and type of food in the stomach, and other physiological conditions

Caffeine is rarely the only stimulant in food or drinks that contain stimulants, though it is the best-known and most-studied. Different people have different reactions to the different kinds of stimulants, and even across kinds of teas, the ratios of the stimulants varies.

In other words, exact measurements of caffeine levels are not particularly meaningful. At best, comparing caffeine levels between teas can provide a general, vague sense of which teas are more stimulating than others. But comparing caffeine levels between different types of foods and drinks isn't helpful. For instance, mate supposedly has less caffeine than tea, though I usually find mate to be more stimulating than tea. Even within the world of tea, two teas that supposedly have the same levels of caffeine often have entirely different effects on me in terms of stimulation. Want to know how a particular tea will affect your body? Drink it and find out, because the result will be unique to you and when you consume your tea. The amount of caffeine supposedly in a particular tea isn't very meaningful.

I think, at best, we can give relative amounts. For instance, "Usually I find tea x to be more stimulating than tea y". To give a concrete example Xell's answer mirrors my own experience - kukicha usually is not as much as a kick in the pants to me as sencha brewed similarly.